Lilly tells Marshall that she had never peed in front of him before, but in the episode Slutty pumpkin, they both go to the bathroom together, because of an elaborate costume of hers.
When Barney takes off his pants he removes the belt from the trousers; but when he puts his pants back on the belt is already in the loops.
The amount of ash on Barney's cigar changes inconsistently between shots.
Barney comments "The only reason to wait a month for sex is if she's 17 years 11 months old," implying the age of consent is 18. The actual age of consent in the state of New York is 17.